#include <string.h>

char* strtok_r(char* restrict s, const char* restrict sep, char** restrict p) {
    if (!s && !(s = *p))
        return NULL;
    s += strspn(s, sep);
    if (!*s)
        return *p = 0;
    *p = s + strcspn(s, sep);
    if (**p)
        *(*p)++ = 0;
    else
        *p = 0;
    return s;
}